Organic light-emitting display apparatus

ABSTRACT

An organic light-emitting display apparatus includes a plurality of first emission units, each including a first organic light-emitting device configured to emit light in at least a first direction and through a first display surface, a plurality of second emission units, each including a second organic light-emitting device configured to emit in a second direction opposite to the first direction and through a second display surface. The first emission units and the second emission units are alternately disposed. The apparatus further includes a transmissive area disposed adjacent to but not overlapping with the plurality of first emission units and the plurality of second emission units when viewed from a direction perpendicular to the first display surface, and capable of transmitting external light through the first and second display surfaces in the transmissive area.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application claims the benefit of Korean Patent Application No.10-2012-0063408, filed on Jun. 13, 2012, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND

1. Field

The present disclosure relates to an organic light-emitting displayapparatus, and more particularly, to a transparent organiclight-emitting display apparatus.

2. Discussion of the Related Technology

Organic light-emitting display apparatuses are widely used in personalportable apparatuses including a moving picture experts group layer 3(MP3) player, a mobile phone, or the like, and TVs, due to its excellentcharacteristics with respect to viewing angles, contrast, responsetimes, power consumption, and the like.

The organic light-emitting display apparatuses have a self-emissioncharacteristic, and thus do not require a separate light source, unlikea liquid crystal display (LCD) apparatus. Therefore, a thickness and aweight of the organic light-emitting display apparatus may be reduced.

Also, the organic light-emitting display apparatus may have atransparent thin-film transistor (TFT) or a transparent organiclight-emitting device, so that the organic light-emitting displayapparatus may be formed as a transparent display apparatus.

When the transparent display apparatus is in a switch-off state, anobject or an image on a side of the transparent display apparatusopposite to a user is visible to the user via patterns of the organiclight-emitting device, the TFT, several wirings, and gaps therebetween.However, although the organic light-emitting display apparatus is thetransparent display apparatus, transmittances of the organiclight-emitting device, the TFT, and the several wirings are notexcellent, and the gaps therebetween are very small, and thustransmittance of the organic light-emitting display apparatus is nothigh.

Also, due to the patterns, i.e., the patterns of the organiclight-emitting device, the TFT, and the several wirings, the user mayview a distorted image. Because a distance between the patterns is inthe range of several hundreds of nm, which is the same level aswavelengths of visible light, scattering of light occurs.

SUMMARY

According to an aspect of the present invention, there is provided anorganic light-emitting display apparatus including a plurality of firstemission units, each including a first organic light-emitting deviceconfigured to emit light in at least a first direction and through afirst display surface; a plurality of second emission units, eachincluding a second organic light-emitting device configured to emitlight in a second direction opposite to the first direction and througha second display surface opposing the first display surface, wherein thefirst emission units and the second emission units are alternatelydisposed; and a transmissive area disposed adjacent to but notoverlapping with the plurality of first emission units and the pluralityof second emission units when viewed from a direction perpendicular tothe first display surface, and capable of transmitting external lightthrough the first and second display surfaces in the transmissive area.

At least one of the first emission units and at least one of the secondemission units may be adjacent to a side of the transmissive area.

The organic light-emitting display apparatus may further include aplurality of first circuit units, each of which is electricallyconnected to one of the plurality of first emission units, and does notoverlap with the connected one of the plurality of first emission unitswhen viewed from the direction, and a plurality of second circuit units,each of which is electrically connected to one of the plurality ofsecond emission units, and overlaps with the connected one of theplurality of second emission units when viewed from the direction.

The organic light-emitting display apparatus may further include aplurality of circuit units, each of which is electrically connected toone of the plurality of first emission units and one of the plurality ofsecond emission units, and overlaps with the connected one of theplurality of second emission units when viewed from the direction.

At least one of the first emission units and at least one of the secondemission units may be adjacent to two opposite sides of the transmissivearea, respectively.

The organic light-emitting display apparatus may further include aplurality of first circuit units, each of which is electricallyconnected to one of the plurality of first emission units, and does notoverlap with the connected one of the plurality of first emission unitswhen viewed from the direction, and a plurality of second circuit units,each of which is electrically connected to one of the plurality ofsecond emission units, and overlaps with the connected one of theplurality of second emission units when viewed from the direction.

The organic light-emitting display apparatus may further include aplurality of circuit units, each of which is electrically connected toone of the plurality of first emission units and one of the plurality ofsecond emission units, and overlaps with the connected one of theplurality of second emission units when viewed from the direction.

At least a portion of the transmissive area may be disposed between atleast one of the plurality of first emission units and at least one ofthe plurality of second emission units.

The organic light-emitting display apparatus may further include asee-through window formed in the transmissive area.

According to another aspect of the present invention, there is providedan organic light-emitting display apparatus including a substrate; aplurality of first pixels formed over the substrate and including aplurality of first emission units configured to emit light in at leastfirst direction and through a first display surface; a plurality ofsecond pixels formed on the substrate, including a plurality of secondemission units configured to emit in a second direction opposite to thefirst direction and through a second display surface opposing the firstdisplay surface, wherein the first pixels and the second pixels arealternately disposed; a plurality of first pixel electrodes, each ofwhich is disposed in one of the plurality of first emission units of theplurality of first pixels, and includes a transparent conductive layeror a transflective conductive layer; a plurality of second pixelelectrodes, each of which is disposed in one of the plurality of secondemission units of the plurality of second pixels, and includes areflective layer; a first opposite electrode facing the plurality offirst pixel electrodes; a second opposite electrode facing the pluralityof second pixel electrodes; a first organic layer interposed between oneof the plurality of first pixel electrodes and the first oppositeelectrode, and including a first emission layer; a second organic layerinterposed between one of the plurality of second pixel electrodes andthe second opposite electrode, and including a second emission layer;and at least one transmissive area disposed adjacent to the plurality offirst pixels and the plurality of second pixels, and capable oftransmitting external light through the first and second displaysurfaces in the transmissive area.

The first opposite electrode and the second opposite electrode may beelectrically connected.

At least one of the first pixels and at least one of the second pixelsmay be adjacent to a side of the transmissive area.

Each of the plurality of first pixels may further include a firstcircuit unit that is electrically connected to the corresponding firstpixel electrode and that does not overlap with the corresponding firstpixel electrode when viewed from a direction perpendicular to the firstdisplay surface, and wherein each of the plurality of second pixels mayfurther include a second circuit unit that is electrically connected tothe corresponding second pixel electrode and that overlaps with thecorresponding second pixel electrode when viewed from the direction.

Each of the plurality of second pixels may further include a circuitunit that is electrically connected to the corresponding second pixelelectrode and the first pixel electrode of an adjacent first pixel, andthat overlaps with the corresponding second pixel electrode.

At least one of the first pixels and at least one of the second pixelsmay be adjacent to two opposite sides of the transmissive area,respectively.

Each of the plurality of first pixels may further include a firstcircuit unit that is electrically connected to the corresponding firstpixel electrode and that does not overlap with the corresponding firstpixel electrode when viewed from a direction perpendicular to the firstdisplay surface, and wherein each of the plurality of second pixels mayfurther include a second circuit unit that is electrically connected tothe corresponding second pixel electrode and that overlaps with thecorresponding second pixel electrode when viewed from the direction.

Each of the plurality of second pixels may further include a circuitunit that is electrically connected to the corresponding second pixelelectrode and the first pixel electrode of an adjacent first pixel, andthat overlaps with the corresponding second pixel electrode when viewedfrom a direction perpendicular to the first display surface.

The organic light-emitting display apparatus may further include asee-through window formed in the transmissive area.

The second opposite electrode may include a metal layer capable ofreflecting light, and the metal layer may include an opening thatcorresponds to at least the see-through window.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent by describing in detail exemplary embodimentsthereof with reference to the attached drawings in which:

FIG. 1 is a cross-sectional view of an organic light-emitting displayapparatus according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view of an organic light-emitting displayapparatus according to another embodiment of the present invention;

FIG. 3 is a plane view of a first pixel and a second pixel that areadjacent to each other in an organic light emission unit of FIG. 1 or 2,according to an embodiment of the present invention;

FIG. 4 is a cross-sectional view taken along a line IV-IV of FIG. 3;

FIG. 5 is a cross-sectional view taken along a line V-V of FIG. 3;

FIG. 6 is a plane view of a first pixel and a second pixel that areadjacent to each other in the organic light emission unit of FIG. 1 or2, according to another embodiment of the present invention;

FIG. 7 is a circuit view illustrating in detail an example of a circuitunit of FIG. 6;

FIG. 8 illustrates another example of the organic light emission unit ofFIG. 1 or 2, according to an embodiment of the present invention;

FIG. 9 is a plane view illustrating an example of a portion A of FIG. 8;and

FIG. 10 is a plane view illustrating another example of the portion A ofFIG. 8.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to the attached drawings.

As used herein, the term “and/or” includes any and all combinations ofone or more of the associated listed items.

Compared to the LCD apparatus, an organic light-emitting displayapparatus may include a dual-emission device. In a dual-emission device,however, the same image may be realized on two sides such that the leftand right of an image realized on one side is reversed in the same imagerealized on the other side.

In addition, it is possible to embody a dual-emission type display bymanufacturing and attaching two independent organic light-emittingdisplay apparatuses to form one display device with dual emission.However, it would be difficult to form this dual-emission display deviceas a transparent display apparatus.

FIG. 1 is a cross-sectional view of an organic light-emitting displayapparatus according to an embodiment of the present invention.

Referring to FIG. 1, the organic light-emitting display apparatusincludes an organic light emission unit 2 that is formed on a surface ofa substrate 1, and an encapsulation unit 3 that encapsulates the organiclight emission unit 2. The substrate may include a display surface onwhich an image is formed.

The encapsulation unit 3 in the present embodiment illustrated in FIG. 1may include an encapsulation substrate 31. The encapsulation substrate31 may be formed as a transparent substrate so as to realize an imagefrom the organic light emission unit 2 and on its surface and to preventoutside air and moisture from penetrating into the organic lightemission unit 2.

Side ends of the substrate 1 and the encapsulation substrate 31 arecombined by using an encapsulation member 32, so that a space 33 betweenthe substrate 1 and the encapsulation substrate 31 is encapsulated. Anabsorbent or a filling member may be arranged in the space 33.

Instead of the encapsulation substrate 31, as shown in FIG. 2, a thinencapsulation film 34 may be formed on the organic light emission unit2, so that the organic light emission unit 2 may be protected fromoutside air. The encapsulation film 34 may have a structure in which aninorganic layer that is formed of silicon oxide or silicon nitride andan organic layer that is formed of epoxy or polyimide are alternatelystacked. However, the structure of the encapsulation film 34 is notlimited thereto and thus any encapsulation structure having atransparent thin film may be used.

FIG. 3 is a plane view of a first pixel 21 and a second pixel 22 thatare adjacent to each other in the organic light emission unit 2,according to an embodiment of the present invention. The first pixel 21includes a 1-1 sub-pixel 21-1, a 1-2 sub-pixel 21-2, and a 1-3 sub-pixel21-3 to realize a full-white color via emission of different colors. Thesecond pixel 22 includes a 2-1 sub-pixel 22-1, a 2-2 sub-pixel 22-2, anda 2-3 sub-pixel 22-3 to realize a full-white color via emission ofdifferent colors. The 1-1 sub-pixel 21-1, the 1-2 sub-pixel 21-2, andthe 1-3 sub-pixel 21-3 may be a red sub-pixel, a green sub-pixel, and ablue sub-pixel, respectively. The 2-1 sub-pixel 22-1, the 2-2 sub-pixel22-2, and the 2-3 sub-pixel 22-3 may be a red sub-pixel, a greensub-pixel, and a blue sub-pixel, respectively.

Each of the 1-1 sub-pixel 21-1, the 1-2 sub-pixel 21-2, and the 1-3sub-pixel 21-3 of the first pixel 21 includes a first emission unit 211and a first circuit unit 212. The first emission unit 211 and the firstcircuit unit 212 may be disposed adjacent to each other and may notoverlap with each other when viewed from a direction perpendicular to adisplay surface of the display device. The first circuit units 212 ofthe 1-1 sub-pixel 21-1, the 1-2 sub-pixel 21-2, and the 1-3 sub-pixel21-3 of the first pixel 21 are electrically connected to the firstemission units 211 of the 1-1 sub-pixel 21-1, the 1-2 sub-pixel 21-2,and the 1-3 sub-pixel 21-3, respectively.

Each of the 2-1 sub-pixel 22-1, the 2-2 sub-pixel 22-2, and the 2-3sub-pixel 22-3 of the second pixel 22 includes a second emission unit221 and a second circuit unit 222. The second emission unit 221 and thesecond circuit unit 222 may be disposed to overlap with each other whenviewed from the direction. The second circuit units 222 of the 2-1sub-pixel 22-1, the 2-2 sub-pixel 22-2, and the 2-3 sub-pixel 22-3 areelectrically connected to the second emission units 221 of the 2-1sub-pixel 22-1, the 2-2 sub-pixel 22-2, and the 2-3 sub-pixel 22-3,respectively.

The first pixel 21 and the second pixel 22 that are adjacent to eachother are adjacent to a transmissive unit or area 23. For example, thefirst pixel 21 and the second pixel 22 that are adjacent to each othermay be adjacent and in parallel to a side of the transmissive unit 23.

The first pixel 21 and the second pixel 22 may realize images indifferent directions. For example, the first emission units 211 of thefirst pixel 21 may be a bottom emission type, and the second emissionunits 221 of the second pixel 22 may be a top-emission type.

Because the second emission units 221 of the second pixel 22 are thetop-emission type, and the second circuit units 222 overlap with thesecond emission units 221 when viewed from the direction, the secondcircuit units 222 do not interfere with the transmissive unit 23, andthus transmittance deterioration may be decreased, and emissionefficiency deterioration in the second emission units 221 due to thesecond circuit units 222 may be decreased.

Because the first emission units 211 of the first pixel 21 are thebottom emission type, and the first circuit units 212 do not overlapwith the first emission units 211 when viewed from the direction,emission efficiency deterioration in the first emission units 211 due tothe first circuit units 212 may also be decreased.

As described above, the first pixel 21 and the second pixel 22 that areadjacent to each other, and the transmissive unit 23 may form one pixelstructure 20.

Accordingly, a pixel circuit formed in the first circuit unit 212 of the1-1 sub-pixel 21-1 and a pixel circuit formed in the second circuit unit222 of the 2-1 sub-pixel 22-1 may selectively or simultaneously allowthe first emission unit 211 and the second emission unit 221 of each ofthe sub-pixels to selectively or simultaneously emit light so as to beequivalent to or to be symmetrical with each other.

When the organic light emission unit 2 of FIGS. 1 and 2 is embodied byhaving a plurality of the pixel structures 20, transmittance via thetransmissive unit 23 may be increased, and thus a transparent orsee-through display apparatus may be embodied, and images that areequivalent to or symmetrical with each other may be selectively orsimultaneously realized on top and bottom surfaces of a displayapparatus.

FIGS. 4 and 5 are cross-sectional views that are respectively takenalong lines IV-IV and V-V of FIG. 3, and illustrate examples of thefirst emission unit 211, the first circuit unit 212, the second emissionunit 221, the second circuit unit 222, and the transmissive unit 23.

As shown in FIGS. 4 and 5, the first circuit unit 212 and the secondcircuit unit 222 are formed on the substrate 1, and here, the firstcircuit unit 212 and the second circuit unit 222 include at leastthin-film transistors (TFTs) T and T′, respectively.

In embodiments, a buffer layer 111 is formed on a surface of thesubstrate 1, and the TFTs T and T′ are formed on the buffer layer 111.

First, a first semiconductor active layer 112 a and a secondsemiconductor active layer 112 b are formed on the buffer layer 111.

The buffer layer 111 may function to prevent penetration of foreignsubstances and to planarize a top surface, and may be formed of variousmaterials capable of performing the functions. For example, the bufferlayer 111 may be formed of inorganic materials including silicon oxide,silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride,titanium oxide, or titanium nitride, organic materials includingpolyimide, polyester, or acryl, or a multi-stack structure includingthese materials. The buffer layer 111 is not necessarily arranged andthus may not be formed.

The first semiconductor active layer 112 a and the second semiconductoractive layer 112 b may be formed of, but is not limited to,polycrystalline silicon and thus may be formed as oxide semiconductors.For example, each of the first semiconductor active layer 112 a and thesecond semiconductor active layer 112 b may be a G-I-Z-Olayer[(In₂O₃)a(Ga₂O₃)b(ZnO)c layer](where, a, b, and c are real numbersthat satisfy a≧0, b≧0, and c>0, respectively).

A gate insulating layer 113 is formed on the buffer layer 111 so as tocover the first semiconductor active layer 112 a and the secondsemiconductor active layer 112 b, and a first gate electrode 114 a and asecond gate electrode 114 b are formed on the gate insulating layer 113.

An interlayer insulating layer 115 is formed on the gate insulatinglayer 113 so as to cover the first gate electrode 114 a and a secondgate electrode 114 b. Then, a first source electrode 116 a and a firstdrain electrode 117 a and a second source electrode 116 b and a seconddrain electrode 117 b are formed on the interlayer insulating layer 115,and contact the first semiconductor active layer 112 a and the secondsemiconductor active layer 112 b, respectively, via contact holes.

However, a structure of the TFTs T and T′ is not limited to theaforementioned structure, and thus the TFTs T and T′ may have one ofvarious structures. In embodiments, the TFT T of the first circuit unit212 and the TFT T′ of the second circuit unit 222 may have differentstructures.

A passivation layer 118 may be formed to cover the first circuit unit212 and the second circuit unit 222 including the TFTs T and T′. Thepassivation layer 118 may be a single or composite insulating layer. Thepassivation layer 118 may be formed of an inorganic material and/or anorganic material.

As shown in FIGS. 4 and 5, a first pixel electrode 241 and a secondpixel electrode 251 are formed on the passivation layer 118. The firstpixel electrode 241 and the second pixel electrode 251 are respectivelyconnected to the first drain electrode 117 a and the second drainelectrode 117 b of the TFTs T and T′ through vias or holes formed in thepassivation layer 118. The first pixel electrode 241 and the secondpixel electrode 251 have structures that are separated from each other.

A pixel defining layer (PDL) 119 is formed on the passivation layer 118so as to cover side ends of the first pixel electrode 241 and the secondpixel electrode 251.

A first organic layer 243 is formed on the first pixel electrode 241,and a first opposite electrode 242 is formed to cover the first organiclayer 243. A first organic light-emitting device 24 is formed as amultilayered body including the first pixel electrode 241, the firstorganic layer 243, and the first opposite electrode 242.

A second organic layer 253 is formed on the second pixel electrode 251,and a second opposite electrode 252 is formed to cover the secondorganic layer 253. A second organic light-emitting device 25 is formedas a multilayered body including the second pixel electrode 251, thesecond organic layer 253, and the second opposite electrode 252.

The first opposite electrode 242 and the second opposite electrode 252may be electrically connected to each other as a common electrode.

The first organic layer 243 and the second organic layer 253 may beformed of the same material. The first organic layer 243 and the secondorganic layer 253 may be formed as a small-molecule organic layer or apolymer organic layer. When the first organic layer 243 and the secondorganic layer 253 are formed as the small-molecule organic layer, inembodiments, each of the first organic layer 243 and the second organiclayer 253 may have a structure in which a hole injection layer (HIL), ahole transport layer (HTL), an emission layer (EML), an electrontransport layer (ETL), an electron injection layer (EIL), and the likeare singularly or multiply stacked, and may be formed by using one ofvarious organic materials including copper phthalocyanine (CuPc),N,N′-Di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB),tris-8-hydroxyquinoline aluminum)(Alq3), or the like. The small-moleculeorganic layer may be formed by using a vacuum deposition method. Here,at least one of the HIL, the HTL, the ETL, and the EIL may be commonlyformed without being patterned for each of the sub-pixels of the firstpixel 21 and the second pixel 22. The EML may be patterned for each ofthe sub-pixels. In this regard, the 1-1 sub-pixel 21-1, the 1-2sub-pixel 21-2, and the 1-3 sub-pixel 21-3, and the 2-1 sub-pixel 22-1,the 2-2 sub-pixel 22-2, and the 2-3 sub-pixel 22-3 may be patterned tohave the same-color emission layers, respectively.

The first pixel electrode 241 and the second pixel electrode 251 mayfunction as an anode electrode, and the first opposite electrode 242 andthe second opposite electrode 252 may function as a cathode electrode.Obviously, polarities of the first pixel electrode 241 and the secondpixel electrode 251 and polarities of the first opposite electrode 242and the second opposite electrode 252 may be switched.

In embodiments, the first pixel electrode 241 may have a sizecorresponding to the first emission unit 211 in each of the sub-pixelsof the first pixel 21. Also, the second pixel electrode 251 may have asize corresponding to the second emission unit 221 in each of thesub-pixels of the second pixel 22.

The first opposite electrode 242 and the second opposite electrode 252may apply a common voltage to all pixels of the organic light emissionunit 2.

The passivation layer 118, the gate insulating layer 113, the interlayerinsulating layer 115, and the PDL 119 may be formed as, but are notlimited to, transparent insulating layers. Here, the substrate 1 hastransmittance that is equal to or less than transmittance of theinsulating layers.

According to the present embodiment, the first pixel electrode 241 maybe formed as a transparent electrode, and the first opposite electrode242 may be a reflective electrode. Thus, the first emission unit 211corresponds to a bottom-emission type in which an image is realizedtoward the first pixel electrode 241.

In embodiments, the second pixel electrode 251 may be an electrodeincluding a reflective layer, and the second opposite electrode 252 maybe a transflective electrode. Thus, the second emission unit 221corresponds to a top-emission type in which an image is realized towardthe second opposite electrode 252.

As described above, when the second pixel electrode 251 is formed as areflective electrode, the pixel circuit formed therebelow is covered bythe second pixel electrode 251. That is, in FIG. 5, a user on an upperside of the second opposite electrode 252 may not view each pattern ofthe TFT T′ below the second pixel electrode 251.

Also, because the second pixel electrode 251 is formed as the reflectiveelectrode, emitted light travels only toward a viewer, so that an amountof light that is lost in a direction away from the viewer may bereduced.

The first pixel electrode 241 is formed as a transparent conductivelayer. The transparent conductive layer may be formed of ITO, IZO, ZnO,or In₂O₃, which has a relatively high work function.

The second pixel electrode 251 may be formed as a multi-stack of atransparent conductive layer and a reflective layer. The transparentconductive layer may be formed of ITO, IZO, ZnO, or In₂O₃, which has arelatively high work function. The reflective layer may be formed of Ag,Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, Yb, or a compound of any ofthese.

The first opposite electrode 242 and the second opposite electrode 252may be formed of a metal having a relatively small work function, e.g.,Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, Yb, or an alloy thereof.The first opposite electrode 242 and the second opposite electrode 252may be formed as thin-layers having relatively high transmittance, and athickness of each of the thin-layers may be from about 100 to about 500Å. The first opposite electrode 242 may further include a reflectivelayer. The reflective layer may be formed of Ag, Mg, Al, Pt, Pd, Au, Ni,Nd, Ir, Cr, Li, Ca, Yb, or a compound of any of these.

A distance between a surface of the reflective layer of the second pixelelectrode 251 and the second opposite electrode 252 may be adjusted toallow optical resonance with respect to a wavelength of light generatedin the EML of the second organic layer 253. Thus, the distance may varyfor each of red, green, and blue sub-pixels. In order to adjust thedistance for the optical resonance, a thickness of at least one of theHIL, the HTL, the ETL, and the EIL may vary for each of red, green, andblue sub-pixels, or an auxiliary layer may be further formed.

The second emission unit 221 having the aforementioned structure maycorrespond to the top-emission type in which an image is realized towardthe second opposite electrode 252, and by adjusting the distance for theoptical resonance, light extraction efficiency may be maximized.

In order to further increase external light transmittance in thetransmissive unit 23, a see-through window 231 may be formed in thetransmissive unit 23.

The see-through window 231 may be embodied by forming an opening in acorresponding region of the transmissive unit 23 so that none of thefirst opposite electrode 242 and the second opposite electrode 252 isformed in the corresponding region. Due to the see-through window 231,external light transmittance of the transmissive unit 23 may beimproved.

As illustrated in FIG. 3, the see-through window 231 may have an areacorresponding to the transmissive unit 23. Thus, the first pixel 21 andthe second pixel 22 may be adjacent and in parallel to a side of thesee-through window 231.

Although FIGS. 4 and 5 illustrate an example in which the see-throughwindow 231 corresponds to the opening formed in the first oppositeelectrode 242 and the second opposite electrode 252, one or moreembodiments of the present invention are not limited thereto, and thusthe see-through window 231 may be further formed in at least one of thePDL 119, the passivation layer 118, the interlayer insulating layer 115,the gate insulating layer 113, and the buffer layer 111.

FIG. 6 is a plane view of a first pixel 21′ and a second pixel 22′ thatare adjacent to each other in the organic light emission unit 2,according to another embodiment of the present invention. Similar to theembodiment illustrated in FIG. 3, the first pixel 21′ includes a 1-1sub-pixel 21′-1, a 1-2 sub-pixel 21′-2, and a 1-3 sub-pixel 21′-3, andthe second pixel 22′ includes a 2-1 sub-pixel 22′-1, a 2-2 sub-pixel22′-2, and a 2-3 sub-pixel 22′-3.

Unlike the embodiment illustrated in FIG. 3, in the present embodimentillustrated in FIG. 6, each of the 1-1 sub-pixel 21′-1, the 1-2sub-pixel 21′-2, and the 1-3 sub-pixel 21′-3 of the first pixel 21′includes a first emission unit 211′ without a circuit unit.

Each of the 2-1 sub-pixel 22′-1, the 2-2 sub-pixel 22′-2, and the 2-3sub-pixel 22′-3 of the second pixel 22′ includes a second emission unit221′ and a circuit unit 223. The second emission unit 221′ and thecircuit unit 223 may overlap with each other when viewed from thedirection. The second emission units 221′ of the 2-1 sub-pixel 22′-1,the 2-2 sub-pixel 22′-2, and the 2-3 sub-pixel 22′-3 of the second pixel22′ are electrically connected to the circuit units 223, and the firstemission unit 211′ of the 1-1 sub-pixel 21′-1, the 1-2 sub-pixel 21′-2,and the 1-3 sub-pixel 21′-3 of the first pixel 21′ are electricallyconnected to the circuit units 223.

Similar to the embodiment illustrated in FIG. 3, the first pixel 21′ andthe second pixel 22′ may realize images in different directions. Forexample, the first emission units 211′ of the first pixel 21′ may be abottom emission type, and the second emission units 221′ of the secondpixel 22′ may be a top-emission type.

As described above, the first pixel 21′ and the second pixel 22′ thatare adjacent to each other, and a transmissive unit 23′ may form onepixel structure 20′.

Pixel circuits formed in the circuit units 223 simultaneously drive thefirst emission units 211′ of the 1-1 sub-pixel 21′-1, the 1-2 sub-pixel21′-2, and the 1-3 sub-pixel 21′-3 of the first pixel 21′, and thesecond emission units 221′ of the 2-1 sub-pixel 22′-1, the 2-2 sub-pixel22′-2, and the 2-3 sub-pixel 22′-3 of the second pixel 22′.

FIG. 7 is a circuit view illustrating in detail an example of thecircuit unit 223 of FIG. 6.

Referring to FIG. 7, a scan line S, a data line D, and a Vdd line V thatis a driving power source are electrically connected to the circuit unit223. Although not illustrated in FIG. 7, according to a configuration ofthe circuit unit 223, other various conductive lines, in addition to thescan line S, the data line D, and the Vdd line V, may be furtherarranged.

The circuit unit 223 includes a first TFT T1 connected to the scan lineS and the data line D, a second TFT T2 connected to the first TFT T1 andthe Vdd line V, and a capacitor Cst connected to the first TFT T1 andthe second TFT T2.

A gate electrode of the first TFT T1 is connected to the scan line S andthus receives a scan signal, a first electrode of the first TFT T1 isconnected to the data line D, and a second electrode of the first TFT T1is connected to the capacitor Cst and a gate electrode of the second TFTT2.

A first electrode of the second TFT T2 is connected to the Vdd line Vand the capacitor Cst, and a second electrode of the second TFT T2 isconnected to each of first electrodes of a first emission TFT T3 and asecond emission TFT T4.

Here, the first TFT T1 corresponds to a switching transistor, and thesecond TFT T2 corresponds to a driving transistor.

A second electrode of the first emission TFT T3 is electricallyconnected to a first organic light-emitting device 24′, and a secondelectrode of the second emission TFT T4 is electrically connected to asecond organic light-emitting device 25′. In the embodiment illustratedin FIG. 6, the first organic light-emitting device 24′ may be arrangedat the first emission unit 211′ of each of the 1-1 sub-pixel 21′-1, the1-2 sub-pixel 21′-2, and the 1-3 sub-pixel 21′-3 of the first pixel 21′,and the second organic light-emitting device 25′ may be arranged at thesecond emission unit 221′ of each of the 2-1 sub-pixel 22′-1, the 2-2sub-pixel 22′-2, and the 2-3 sub-pixel 22′-3 of the second pixel 22′.

Gate electrodes of the first emission TFT T3 and the second emission TFTT4 are electrically connected to separate emission signal lines,respectively.

In the example shown in FIG. 7, all of the TFTs T1 through T4 correspondto, but are not limited to, a p-type, and thus at least one of them maybe formed as an n-type. The number of the TFTs T1 through T4 and thecapacitor Cst is not limited to the example, and thus, according to apixel circuit unit 223, two or more TFTs and at least one capacitor maybe further arranged.

According to the aforementioned configuration of the circuit unit 223,image information input via the data line D is realized by the firstorganic light-emitting device 24′ when the first emission TFT T3 isopen, and image information input via the data line D is realized by thesecond organic light-emitting device 25′ when the second emission TFT T4is open, so that the first organic light-emitting device 24′ and thesecond organic light-emitting device 25′ may realize different images.Thus, an image on a top emission surface and an image on a bottomemission surface may be reversed like a mirror image with respect toeach other by time-division driving so that dual-emission may beachieved in an unseen manner. Obviously, when the same switching signalis applied to the first emission TFT T3 and the second emission TFT T4while the same data signal is applied thereto, reversed mirror imagesmay be viewed on a top surface and a bottom surface. As described above,the circuit unit 223 may enable various screen displays while the firstorganic light-emitting device 24′ and the second organic light-emittingdevice 25′ share a basic configuration of a pixel circuit unit.

FIG. 8 illustrates disposition of pixels in the organic light emissionunit 2, according to an embodiment of the present invention. In theembodiment illustrated in FIG. 8, first pixel structures 201 aredisposed at every odd row O, and second pixel structures 202 aredisposed at every even row E. The first pixel structures 201 may be forbottom emission and transmittance of external light, and the secondpixel structures 202 may be for top emission and transmittance ofexternal light. The first pixel structures 201 and the second pixelstructures 202 may simultaneously or selectively realize the same ordifferent images. In the embodiment illustrated in FIG. 8, the samepixel structures are disposed at, but are not limited to, every row, andthus the same pixel structures may be disposed at every column.

FIG. 9 illustrates an example of a portion A of FIG. 8.

The first pixel structure 201 disposed at the odd row O may have thefirst pixel 21. The first pixel 21 includes the 1-1 sub-pixel 21-1, the1-2 sub-pixel 21-2, and the 1-3 sub-pixel 21-3, which realize afull-white color via emission of different colors. Each of the 1-1sub-pixel 21-1, the 1-2 sub-pixel 21-2, and the 1-3 sub-pixel 21-3 ofthe first pixel 21 includes the first emission unit 211 and the firstcircuit unit 212.

The first emission unit 211 and the first circuit unit 212 may bedisposed adjacent to each other and may not overlap with each other whenviewed from the direction. The first circuit units 212 of the 1-1sub-pixel 21-1, the 1-2 sub-pixel 21-2, and the 1-3 sub-pixel 21-3 ofthe first pixel 21 are electrically connected to the first emissionunits 211 of the 1-1 sub-pixel 21-1, the 1-2 sub-pixel 21-2, and the 1-3sub-pixel 21-3 of the first pixel 21, respectively.

The 1-1 sub-pixel 21-1, the 1-2 sub-pixel 21-2, and the 1-3 sub-pixel21-3 are adjacent to the transmissive unit 23. An opening window 231′may be formed in the transmissive unit 23, and in this regard, the 1-1sub-pixel 21-1, the 1-2 sub-pixel 21-2, and the 1-3 sub-pixel 21-3 areadjacent and in parallel to a side of the opening window 231′.

The second pixel structure 202 disposed at the even row E may have thesecond pixel 22. The second pixel 22 includes the 2-1 sub-pixel 22-1,the 2-2 sub-pixel 22-2, and the 2-3 sub-pixel 22-3, which realize afull-white color via emission of different colors.

Each of the 2-1 sub-pixel 22-1, the 2-2 sub-pixel 22-2, and the 2-3sub-pixel 22-3 of the second pixel 22 includes the second emission unit221 and the second circuit unit 222. The second emission unit 221 andthe second circuit unit 222 may be disposed to overlap with each otherwhen viewed from the direction. The second pixels 222 of the 2-1sub-pixel 22-1, the 2-2 sub-pixel 22-2, and the 2-3 sub-pixel 22-3 areelectrically connected to the second emission units 221 of the 2-1sub-pixel 22-1, the 2-2 sub-pixel 22-2, and the 2-3 sub-pixel 22-3,respectively.

The 2-1 sub-pixel 22-1, the 2-2 sub-pixel 22-2, and the 2-3 sub-pixel22-3 are adjacent to the transmissive unit 23. The opening window 231′may be formed in the transmissive unit 23, and in this regard, the 2-1sub-pixel 22-1, the 2-2 sub-pixel 22-2, and the 2-3 sub-pixel 22-3 areadjacent and in parallel to a side of the opening window 231′.

Detailed descriptions of the aforementioned elements are the same asthose of the embodiment illustrated in FIG. 3, and thus are omittedhere.

FIG. 10 illustrates another example of the portion A of FIG. 8.

Each of the sub-pixels 21′-1, 21′-2, and 21′-3 of a first pixelstructures 201′ that disposed at the odd row O includes the firstemission unit 211′ without a circuit unit, similar to the embodimentillustrated in FIG. 6.

Each of the sub-pixels 22′-1, 22′-2, and 22′-3 of a second pixelstructures 202′ that is disposed at the even row E includes the secondemission unit 221′ and the circuit unit 223, similar to the embodimentillustrated in FIG. 6. The second emission unit 221′ and the circuitunit 223 may overlap with each other when viewed from the direction. Thesecond emission units 221′ of the sub-pixels 22′-1, 22′-2, and 22′-3 ofthe second pixel 22′ are electrically connected to the circuit units223, respectively, and the first emission units 211′ of the sub-pixels22′-1, 22′-2, and 22′-3 of the first pixel 21′ are electricallyconnected to the circuit units 223, respectively.

Detailed descriptions of the aforementioned elements are the same asthose of the embodiment illustrated in FIG. 6, and thus are omittedhere.

As described above, in the embodiments of FIGS. 8 through 10, users on atop surface side and a bottom surface side of a transparent orsee-through display may simultaneously or respectively view the same ordifferent images, and may view an image that is transmitted to both thetop surface side and the bottom surface side.

While embodiments of the present invention have been particularly shownand described, it will be understood by those of ordinary skill in theart that various changes in form and details may be made therein withoutdeparting from the spirit and scope of the present invention as definedby the following claims.

What is claimed is:
 1. An organic light-emitting display apparatuscomprising: a plurality of first emission units, each comprising a firstorganic light-emitting device configured to emit light in at least afirst direction and through a first display surface; a plurality ofsecond emission units, each comprising a second organic light-emittingdevice configured to emit light in a second direction opposite to thefirst direction and through a second display surface opposing the firstdisplay surface, wherein the first emission units and the secondemission units are alternately disposed; and a transmissive areadisposed adjacent to but not overlapping with the plurality of firstemission units and the plurality of second emission units when viewedfrom a direction perpendicular to the first display surface, and capableof transmitting external light through the first and second displaysurfaces in the transmissive area.
 2. The organic light-emitting displayapparatus of claim 1, wherein at least one of the first emission unitsand at least one of the second emission units are adjacent to a side ofthe transmissive area.
 3. The organic light-emitting display apparatusof claim 2, further comprising: a plurality of first circuit units, eachof which is electrically connected to one of the plurality of firstemission units, and does not overlap with the connected one of theplurality of first emission units when viewed from the direction, and aplurality of second circuit units, each of which is electricallyconnected to one of the plurality of second emission units, and overlapswith the connected one of the plurality of second emission units whenviewed from the direction.
 4. The organic light-emitting displayapparatus of claim 2, further comprising a plurality of circuit units,each of which is electrically connected to one of the plurality of firstemission units and one of the plurality of second emission units, andoverlaps with the connected one of the plurality of second emissionunits when viewed from the direction.
 5. The organic light-emittingdisplay apparatus of claim 1, wherein at least one of the first emissionunits and at least one of the second emission units are adjacent to twoopposite sides of the transmissive area, respectively.
 6. The organiclight-emitting display apparatus of claim 5, further comprising: aplurality of first circuit units, each of which is electricallyconnected to one of the plurality of first emission units, and does notoverlap with the connected one of the plurality of first emission unitswhen viewed from the direction, and a plurality of second circuit units,each of which is electrically connected to one of the plurality ofsecond emission units, and overlaps with the connected one of theplurality of second emission units when viewed from the direction. 7.The organic light-emitting display apparatus of claim 5, furthercomprising a plurality of circuit units, each of which is electricallyconnected to one of the plurality of first emission units and one of theplurality of second emission units, and overlaps with the connected oneof the plurality of second emission units when viewed from thedirection.
 8. The organic light-emitting display apparatus of claim 1,wherein at least a portion of the transmissive area is disposed betweenat least one of the plurality of first emission units and at least oneof the plurality of second emission units.
 9. The organic light-emittingdisplay apparatus of claim 1, further comprising a see-through windowformed in the transmissive area.
 10. An organic light-emitting displayapparatus comprising: a substrate; a plurality of first pixels formedover the substrate and comprising a plurality of first emission unitsconfigured to emit light in at least a first direction and through afirst display surface; a plurality of second pixels formed over thesubstrate, and comprising a plurality of second emission unitsconfigured to emit light in a second direction opposite to the firstdirection and through a second display surface opposing the firstdisplay surface, wherein the first pixels and the second pixels arealternately disposed; a plurality of first pixel electrodes, eachdisposed in one of the plurality of first emission units of theplurality of first pixels, and comprising a transparent conductive layeror a transflective conductive layer; a plurality of second pixelelectrodes, each of which is disposed in one of the plurality of secondemission units of the plurality of second pixels, and comprises areflective layer; a first opposite electrode facing the plurality offirst pixel electrodes; a second opposite electrode facing the pluralityof second pixel electrodes; a first organic layer interposed between oneof the plurality of first pixel electrodes and the first oppositeelectrode, and comprising a first emission layer; a second organic layerinterposed between one of the plurality of second pixel electrodes andthe second opposite electrode, and comprising a second emission layer;and at least one transmissive area disposed adjacent to the plurality offirst pixels and the plurality of second pixels, and capable oftransmitting external light through the first and second displaysurfaces in the transmissive area.
 11. The organic light-emittingdisplay apparatus of claim 10, wherein the first opposite electrode andthe second opposite electrode are electrically connected.
 12. Theorganic light-emitting display apparatus of claim 10, wherein at leastone of the first pixels and at least one of the second pixels areadjacent to a side of the transmissive area.
 13. The organiclight-emitting display apparatus of claim 12, wherein each of theplurality of first pixels further comprises a first circuit unit that iselectrically connected to the corresponding first pixel electrode andthat does not overlap with the corresponding first pixel electrode whenviewed from a direction perpendicular to the first display surface, andwherein each of the plurality of second pixels further comprises asecond circuit unit that is electrically connected to the correspondingsecond pixel electrode and that overlaps with the corresponding secondpixel electrode when viewed from the direction.
 14. The organiclight-emitting display apparatus of claim 12, wherein each of theplurality of second pixels further comprises a circuit unit that iselectrically connected to the corresponding second pixel electrode andthe first pixel electrode of an adjacent first pixel, and that overlapswith the corresponding second pixel electrode when viewed from thedirection.
 15. The organic light-emitting display apparatus of claim 10,wherein at least one of the first pixels and at least one of the secondpixels are adjacent to two opposite sides of the transmissive area,respectively.
 16. The organic light-emitting display apparatus of claim15, wherein each of the plurality of first pixels further comprises afirst circuit unit that is electrically connected to the correspondingfirst pixel electrode and that does not overlap with the correspondingfirst pixel electrode when viewed from a direction perpendicular to thefirst display surface, and wherein each of the plurality of secondpixels further comprises a second circuit unit that is electricallyconnected to the corresponding second pixel electrode and that overlapswith the corresponding second pixel electrode when viewed from thedirection.
 17. The organic light-emitting display apparatus of claim 15,wherein each of the plurality of second pixels further comprises acircuit unit that is electrically connected to the corresponding secondpixel electrode and the first pixel electrode of an adjacent firstpixel, and that overlaps with the corresponding second pixel electrodewhen viewed from a direction perpendicular to the first display surface.18. The organic light-emitting display apparatus of claim 10, furthercomprising a see-through window formed in the transmissive area.
 19. Theorganic light-emitting display apparatus of claim 18, wherein the secondopposite electrode comprises a metal layer capable of reflecting light,and the metal layer comprises an opening that corresponds to at leastthe see-through window.